Retrospective cohort study of locally ablative therapies in oligometastatic breast cancer

The potential survival benefit of surgery or ablative treatment for de novo oligometastic breast cancer (dnmBC) is not clear. A retrospective cohort study using the National Cancer Database (2010-2020) evaluated the association of surgical and/or locally ablative treatment of the primary and/or metastatic sites with overall survival in patients with single-site (brain, bone, liver, or lung) oligometastatic dnmBC receiving systemic therapy. Study groups included no locally ablative therapy (NLT), primary breast tumor resection only (BR), metastatic site ablative therapy only (MT), and both therapies (BR+MT). Primary outcome measure was overall survival (OS). Among 22,433 patients (median age 61 years; median follow-up 61.5 months), bone-only metastases were most common (66.8%). Locally ablative therapies were uncommon (BR+MT 6.4%; MT 10.6%; BR 15.3%; NLT 67.7%). Older age and higher comorbidity score were associated with NLT. Compared with NLT, BR (HR 0.62; 95% CI 0.58-0.67) and BR+MT (0.60; 0.54-0.67) were associated with improved survival, whereas OS was worse with MT (1.22; 1.14-1.31). The authors conclude that results of this cohort study suggest that few patients with single-site dnmBC undergo surgical/ablative therapy, although BR+MT and BR only were associated with improved OS.